ROSA26Flpo deleter mice promote efficient inversion of conditional gene traps in vivo

Gene trap mutagenesis in embryonic stem cells is an important tool to help elucidate gene function in current mouse mutagenesis efforts. Vector systems based on inversion of the gene trap module have recently been devised to allow for conditional mutagenesis. However, additional efforts are needed to improve this technology including improving the efficiency of site-specific recombinases required to manipulate these conditional vectors in vivo. Here we describe a mouse line carrying the codon-optimized FLP recombinase Flpo at the ROSA26 locus that functions at higher efficiency than a similar Flpe line in mediating the DNA inversion of a conditional gene trap cassette in vivo.